Improvements in semiconductor materials and in the packaging of microelectronic devices, such as integrated circuits and light-emitting diodes (“LEDs”), have enabled many new applications for these devices but have also resulted in new technical challenges. For example, the efficacy of LEDs has improved to the point that their use in exterior automotive lighting is technically and economically feasible, including for such high light output functions as headlamps. However, one challenge is the need to dissipate significant quantities of heat generated by these newer LEDs, which have ever-increasing power densities. The performance of LEDs is particularly sensitive to heat because excessive junction temperatures not only limit the light output of an LED but may also shorten its operating life significantly. Therefore, it is critical that heat generated by the LED be transferred away from the LED at a rate great enough to maintain the interface between the different semiconductor materials comprising the LED (i.e., the junction) within an acceptable operating temperature range.
For LED usage in an automotive headlamp, the heat dissipation problem is further compounded by the operating environment of an automotive headlamp, which typically combines exposure to high temperatures from the engine compartment, limited packaging volume due to the space constraints at the front end of an automobile, and a fully enclosed package needed to prevent dust and moisture from degrading the performance of the headlamp. Known solutions, such as conventional heat sinks with large fins or active cooling mechanisms, are costly and bulky and are not practical solutions for an LED headlamp application. The use of cooling fans adds mass, volume, and cost to a headlamp and requires additional power consumption, at least partially negating a primary advantage of using LEDs. Likewise, due in part to the enclosed package of a headlamp, conventional heat sinks must be heavy and bulky to effectively cool the LEDs. Accordingly, a need exists for a heat sink device for use with LEDs in a vehicle headlamp that reduces mass, volume, and the need for additional power requirements.